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Station Paper No. 98 



December 1958 



Silvical Characteristics of Loblolly Pine 



by 

Karl F. Wenger 



SOUTHEASTERN FOREST 
EXPERIMENT STATION 
Asheville, North Carolina 

flodeph 3. Peckanec, 
Jul rector 








U. S. DEPARTMENT OF AGRICULTURE - FOREST SERVICE 



Digitized by the Internet Archive 

in 2012 with funding from 

LYRASIS Members and Sloan Foundation 



http://archive.org/details/silvicalcharacteOOweng 



Silvical Characteristics of Loblolly Pine 

(Pinus taeda L. ) 

by 

Karl F. Wenger 
Southeastern Forest Experiment Station 

Because of its wide range, its occurrence in pure stands, its abundance, 
and its versatility in use, loblolly pine ( Pinus taeda ) is the principal commer- 
cial species in the southeastern United States (fig. 1). It grows in the Coastal 
Plain and Piedmont from central Maryland and Delaware south to central 
Florida and west to eastern Texas (fig. 2) (72). It does not grow in the Mis- 
sissippi River bottoms and is scarce in the deep, coarse sands of the lower 
Gulf Coastal Plain and sandhills of North and South Carolina. 

HABITAT CONDITIONS 

CLIMATIC 

The climate of the loblolly pine range is humid, with long, hot summers 
and mild winters. Average annual rainfall varies from 40 to 60 inches per year; 
it is least in Maryland and Delaware and at the western end of the range in east 
Texas ( 124) . Along the Gulf Coast it averages 60 inches. Summer is usually 
the wettest season and autumn the driest along the mid- Atlantic Coast. In the 
western portion of the range, rainfall is more uniformly distributed through 
the year, but summer droughts occur often enough to be a serious obstacle to 
natural regeneration and planting of the species. 

The frost-free period lasts from 6 months in the North to 10 months in 
the South. July temperatures average over 75° F. and frequently exceed 100°; 
January temperatures average 36° to 63° and occasionally go down to -10° in 
the northern and western portions of the range. 

The distribution of loblolly pine is associated with the average winter 
temperature, and the frequency and intensity of both winter and summer rain- 
fall (57). During both winter and summer, the area within the range of loblolly 
pine has a greater number of days with rain and a greater frequency of effec- 
tive amounts of rain (more than 0.50 inch) than the area immediately outside 
the range. The area inside also has a higher average temperature in winter. 
In spring and autumn, the weather inside and outside the range is more nearly 
the same. The main factor limiting northern extension of the species is prob- 
ably temperature, but the western extension is probably limited by precipitation. 
Low air temperatures damage aerial portions, and low soil temperatures retard 
water absorption more in loblolly pine than in native northern species (65). 
Damage by snow and sleet, which is less frequent within the range, may also 
be a factor limiting the northern extension. 









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Figure 1. --Mature loblolly pine tree in the Crossett Experimental Forest, Crossett, Arkansas. 



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EDAPHIC 

Loblolly pine occurs on a wide variety of soils, from the flat, poorly 
drained, ground-water podzols of the lower Coastal Plain to the old residual 
soils of the upper Piedmont. It grows best in soils with poor surface drain- 
age, a deep surface layer, and a firm subsoil (48, 150 ). 

Such soils are common in the lower Coastal Plain and in the flood 
plains of the larger rivers. Prominent examples are the Coxville and Bladen 
series; with deep surface layers these soils have a site index for loblolly of 
90 to 95 feet (48). In the same category is the Elkton series: poorly drained, 
very plastic soils which have an average site index of 95 feet. Most produc- 
tive are the river bottom or terrace soils, notably the Roanoke series in the 
east and the Ocklockonee in the west; these are fairly heavy soils that have 
site indices of over 100 feet (2A, _48). In the Coastal Plain, the productivity 
of soils decreases with improvement in surface drainage. The presence of a 
hardpan within the root profile, as in the Leon series, drastically reduces 
the productivity. Deep, excessively drained sands are also very low in site 
quality ( 24 ) unless the water table lies within reach of the tree roots; with 
high water tables sands may have site indices of 90 to 100 feet. 

In the inland and Piedmont regions, where surface drainage is well- 
developed, the physical characteristics of the soil, rather than drainage, 
determine the availability of moisture, and uneroded soils with a deep sur- 
face layer and a friable subsoil are best (J36). Common in this category are 
soils of the Durham, Georgeville, Appling, Cecil, Davidson, and Lloyd 
series, which have site indices of 80 to 100 feet when not eroded. The least 
productive are eroded soils with a very plastic subsoil. Iredell, Orange, 
and Whitestore (red phase) series fall in this group; they are practically 
worthless when the A horizon is gone, with site indices of less than 40 feet. 

PHYSIOGRAPHIC 

The range of loblolly pine extends over two main physiographic regions, 
the Coastal Plain and the Piedmont. The Coastal Plain is generally very flat 
near the coast but becomes rolling and even sharply hilly in the inland reaches 
with elevations ranging up to 1,000 feet in Georgia. Topography in the Pied- 
mont is more rolling than in the Coastal Plain, with highly developed drainage 
patterns and generally heavier soils. Elevations range up to 1,500 feet. In 
northern Alabama and Georgia, loblolly pine grows at elevations up to and 
over 2,000 feet. 

The rougher topography of the Piedmont results in greater variations 
in site than in the Coastal Plain. Loblolly pine site indices generally in- 
crease from ridge tops to bottoms but this variation seems to be related to 
soil differences rather than to slope position or steepness (35). Soil fea- 
tures that determine site quality, such as surface soil thickness and sub- 
soil consistency, are loosely correlated with topography, but past land use, 
differences in soil parent material, and other factors also affect soil profile 
development and cause variations in site quality independent of topography. 



- 4 



Because of plentiful rainfall, rolling topography, and soil physical char- 
acteristics, the upland soils of the Piedmont and many sections of the upper 
Coastal Plain are subject to moderate to severe sheet and gully erosion 
when exposed and unprotected. The loss of surface layers in the past has un- 
doubtedly contributed to the prevailing poor site quality of upland soils in the 
region (39). 

BIOTIC 

Pure loblolly pine stands are widespread throughout the range where 
moisture is comparatively plentiful (fig. 3). In general, the main associate 
is sweetgum ( Liquidambar styraciflua), but on well-drained sites shortleaf 
pine ( Pinus echinata ), southern red oak ( Quercus falcata ), post oak (Quercus 
stellata ), and blackjack oak ( Quercus marilandica ) are frequently found with 
it. On poorly drained sites black tupelo ( Nyssa sylvatica ), water oak (Quercus 
nigra) , yellow-poplar ( Liriodendron tulipifera ), and pond pine ( Pinus serotina), 
and in the far south slash pine ( Pinus elliottii ) and laurel oak (Quercus 
laurifolia ), usually occur in loblolly pine stands ( 113 ). 

In east Texas, southern Arkansas, Louisiana, and to a lesser extent in 
other states, mixtures of loblolly pine and shortleaf pine occur, with short- 
leaf pine predominating on the drier ridges and loblolly pine on the wetter 
sites. Commonly associated with these species are sweetgum, black tupelo, 
hickories ( Carya spp. ), southern red oak, scarlet oak ( Quercus coccinea ), 
black oak ( Quercus velutina) , white oak ( Quercus alba) , post oak, and minor 
species. 

Loblolly pine also grows in mixtures with hardwoods throughout its 
range. On wet sites sweetbay ( Magnolia virginiana) , redbay (Persea borbonia), 
black tupelo, swamp tupelo ( Nyssa sylvatica var. biflora ), and sweetgum are 
prominent in the hardwood component; water oak, laurel oak, willow oak 
( Quercus phellos ),red maple ( Acer rubrum) , white ash ( Fraxinus americana ), 
green ash ( Fraxinus pennsylvanica ), and American elm (Ulmus americana ) 
are frequently present. On drier sites southern red oak, white oak, northern 
red oak ( Quercus rubra ), hickories, common persimmon (Diospyros virginiana ), 
and scarlet oak are the most common hardwoods, and shortleaf and longleaf 
pine ( Pinus palustris ) are frequent associates. 

In the Piedmont, and in the Coastal Plain of northern Virginia and 
Maryland, loblolly pine also occurs with Virginia pine ( Pinus virginiana ). In 
northern Mississippi, Alabama, and in Tennessee it is a minor associate in 
the eastern redcedar-hardwood type. On moist sites, loblolly is found in the 
longleaf pine type, the longleaf pine- slash pine type, and in the slash pine- 
hardwood type. In the flood plains of major rivers it is a minor associate in 
the swamp chestnut oak- cherrybark oak type. On moist lower slopes in the 
Atlantic Coastal Plain it is an important element in the sweetgum-yellow- 
poplar type. In bays, ponds, swamps, and marshes of the Coastal Plain it 
is a common associate in the pond pine type, the cabbage palmetto- slash 
pine type, and in the sweetbay- swamp tupelo- red maple type ( 1 13 ). 



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Because of the wide range of sites and the numerous types in which lob- 
lolly occurs, a great variety of lesser vegetation may be found in association 
with it and a list of even the most common would be quite lengthy. Worthy of 
mention are waxmyrtle ( Myrica cerifera ), pepperbush ( Clethra alnifolia ), 
gallberry (Ilex glabra) , viburnums ( Viburnum spp.), and a great variety of 
ericaceous shrubs. 

In the natural state, mycorrhizae usually occur on loblolly pine. In- 
fection by several species of fungi causes proliferation of the short roots, 
characterized by repeated dichotomous branching. This proliferation and the 
accompanying mantles of fungal hyphae greatly increase the absorbing surface, 
and conifers in infertile soil without mycorrhizae are very low in mineral 
content compared to those with mycorrhizae. Mycorrhizae apparently can also 
supply carbohydrates from the soil, although they seem primarily dependent on 
those in the plant ( 148 ). They also supply nitrogen compounds, and may be 
able to supply vitamins. Among the fungi capable of producing mycorrhizae 
in loblolly pine, the following have been identified (42, 55): Boletus granulatus , 
Boletus exinus, Boletus brevipes , Boletus chromapes , Boletus subluteus , 
Boletinus pictus, Cantharellus cibarius, Cenococcum graniforme , Russula 
lepida , and Amanita muscaria . 

Few of the animals that live within the range of loblolly pine are associ- 
ated with it by a closer tie than the accident of location. Probably the most 
noteworthy is the red-cockaded woodpecker ( Dryobates borealis) (115). This 
bird invariably digs its nesting cavity in a living pine tree with red heart 
( Fomes pini) . When the cavity is finished, the bird pecks the bark all around 
the entrance hole, causing a heavy flow of pitch. The surface around the 
entrance hole thus becomes very sticky, presumably keeping out intruders. 
Among other birds frequently found in pine forests in the South are the brown- 
headed nuthatch ( Sitta pusilla ), the pine-woods sparrow (Peucaea aestiyales 
aestivales ), the southern pine finch ( Peucaea aestivales bachmani ), the pine 
warbler ( Dendroica vigorsi ), and the prairie warbler ( Dendroica discolor) (1 15). 

Four-footed animals are scarce in full stands, but after clear cutting, 
rodent populations increase rapidly. White-footed mice and red mice 
( Peromyscus spp.), harvest mice ( Reithrodontomys humulis ), pine mice 
( Microtus pennsylvanicus ), cottonrats ( Sigmodon hispidus ), and short-tailed 
shrews ( Blarina brevicauda) are common in cutover areas in eastern North 
Carolina ( 121 ). Gray squirrels ( Sciurus caroliniensis ) are fond of pine seed 
and begin to shell out cones in late summer, as soon as the seeds are well 
filled. 




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LIFE HISTORY OF THE SPECIES 

SEEDING HABITS 

Flowering and fruiting . --The development of loblolly pine seed requires 
nearly three growing seasons from the time of flower bud initiation. Flower 
buds are formed during midsummer, some time after the middle of June, but 
do not become visible until early autumn. Staminate flower buds can be seen 
in the South Atlantic Coastal Plain during October as small knobs around the 
base of vegetative buds. Later, some vegetative buds develop pointed swell- 
ings near the apex, which are pistillate flower buds. These flower buds grow 
rapidly in late winter and for a short time before flowering the staminate buds 
are very prominent. 

Vegetative growth begins about March 1 in the Gulf States and about 6 
weeks later near the North Carolina-Virginia boundary (44). Flowers mature 
and pollen cast begins about 10 days later ( 131 ). The staminate flowers are 
long, yellow catkins, and the pistillate flowers are small, pink or red strobili. 
Pollination lasts 7 to 10 days. Staminate flowers usually are the most plentiful 
and are borne all over the crown, while pistillate flowers tend to be concen- 
trated in the upper portions of the crown. On the same tree, staminate flowers 
tend to mature before pistillate flowers ( 128 ). Thus, pollination depends largely 
on pollen from neighboring trees and may be inhibited if trees shed pollen at 
different times or are too far apart. In general, pine pollen is not carried 
in effective quantities farther than 300 feet, and most falls much closer to the 
source ( 146 ). 

Within the pistillate strobili the growing pollen tubes do not reach the em- 
bryo sac to fertilize the egg cells until late the following spring. By that time, 
the strobili have become conelets one-half to three-fourths of an inch long. 
Growth of cones and seed is rapid during the second season, after fertilization 
occurs. 

Cones mature and seed ripens usually during the early part of October. 
Time of seed ripening does not appear to vary greatly with latitude (44). 
Individual cones may contain from less than 20 to more than 200 seeds, sound 
and defective ( 131 ).—/ The percentage sound may vary from about 15 percent 
up to nearly 100 percent. In southeastern Virginia, the average number of 
sound seeds per cone varied from 30 in stands averaging only 1 cone per tree 
up to 110 in stands averaging 150 cones per tree.— The over- all average 
was 57 sound seeds per cone. 

The seeds vary in size from 16,000 to 25,000 per pound and average 
18,400 per pound (126). 



1/ Records of the Tidewater Forest Research Center, Franklin, Virginia, 
1952. 

2/ Wenger, K. F. Seed tree stimulation study. 1951. (Report on file, 
Southeast. Forest Expt. Sta.) 



8 - 



Seed production . --Individual loblolly pine trees occasionally produce 
cones and viable seed at less than 10 years of age. Pistillate flowers have 
been observed on 5-year-old trees, staminate flowers on 6-year-old trees 
( 106 ), and viable seed have been obtained from 9-year-old trees (132). But 
appreciable quantities of seed are not produced until much later. Seed pro- 
duction of dominant and codominant trees in undisturbed, even-aged stands 
increases gradually until the trees are 30 to 50 years old and 12 inches or 
more in diameter (99). It then increases rapidly until the full potential is 
attained. However, the viability of seed from young trees just beginning to 
bear is as high as that of seed from older trees ( 131 ). 

Although loblolly pine stands are capable of heavy seed production to 
advanced ages, seed crops fluctuate widely from negligible amounts in some 
years to nearly a million seeds per acre in other years. Seed crops of a 
70-year-old stand in North Carolina Piedmont varied from 18,000 to nearly 
300,000 seed per acre during 13 years from 1936 to 1948 ( 101 ). Seed pro- 
duction tends to be better in the coastal portions than in the inland portions 
of the loblolly pine range ( 128) , and annual seed crops of one 95-year-old 
and two 145-year-old stands in northeastern North Carolina ranged from 
50,000 to 832,000 seed per acre from 1947 to 1954. A partially cut 35- to 
45-year-old stand in coastal South Carolina produced 1.4 million seeds per 
acre in 1955, which is apparently the greatest seedfall recorded in loblolly 
pine up to that year (77). 

The annual fluctuations in seed crops depend mainly on weather and 
the physiological status of the trees at the time of flower bud formation. In 
the three stands in northeastern North Carolina, the size of seed crop was 
positively correlated with the May- to- July rainfall of 2 years earlier and 
negatively correlated with the size of the seed crop 2 years earlier ( 142 ). 

Although conditions may favor a heavy set of flower buds, many agen- 
cies may reduce or destroy the cone crop before maturity. Flowers may be 
destroyed by subfreezing temperatures, heavy rain, hail, or strong winds, 
or rainy weather may inhibit or prevent pollination. Drought may retard 
development, and insects damage both cones and seed. 

Cone damage varies from year to year, usually amounting to 10 to 40 
percent but may often be more or less in any given locality (63). Cone losses 
on individual seed trees in southeastern Virginia, caused mainly by insects, 
varied from 2 to 100 percent in one year and from 4 to 71 percent in the follow- 
ing year. Losses were greater in small crops than in large crops, and trees 
that sustained heavy losses in one year also had heavy losses in the next year. 
Most of the insect damage probably is caused by the larvae of a small moth, 
Dioryctria amatella (63), but cone beetles, mainly Conophthorus taedae, may 
also cause appreciable losses (40). Another small moth, Laspeyresia toreuta , 
destroys a small proportion of the individual seeds without otherwise damag- 
ing the cones (63). Insect damage tends to be higher in older stands and on 
better sites. 



9 - 



The quality of seed also varies from year to year with the size of the 
seed crop. In both the Piedmont and Coastal Plain of North Carolina via- 
bility ranged, on the average, from a little more than 40 percent in light 
crops to nearly 80 percent in heavy crops ( 101 , 143 ). In individual stands, 
viability as low as 25 percent occurred. 

Individual dominant and codominant trees in undisturbed stands may 
bear as many as 500 cones but most trees bear less than 100 cones. Inter- 
mediate and suppressed trees may never produce good crops. Fruitfulness 
apparently is hereditary to some degree, and cone crops of individual trees 
are closely related to past fruitfulness ( 45 , 52, 99, 137). Cone crops are 
also proportional to diameter at breast height, and crown volume and crown 
density have been found to affect size of cone crops (53). 

In the Atlantic Coastal States, cone and seed production of individual 
dominant and codominant trees released from competition and of stands par- 
tially cut increased 2- to 10-fold three growing seasons later (46, 99 , 1 19 , 137 ) 
Trees of larger diameter and greater past fruitfulness produced much larger 
crops after release than smaller or less fruitful trees. As many as 1,500 
cones may develop on some trees after release but most trees bear less than 
500 cones. The response to release is greater when it coincides with good 
seed years; in partially cut stands it seems to be proportional to the intensity 
of cutting. It usually persists for several succeeding crops but eventually 
subsides (46, 137 ). 

The cone crop in the third succeeding fall is larger if the release cut- 
ting is done before late spring. In the South Atlantic Coastal Plain the crit- 
ical period is some time during late June or July- -release during or after 
that period is not reflected in cone crop until the fourth succeeding year. 
The reduction in transpiration accompanying the removal of competing trees, 
which is probably equal to several inches of rain, may be the primary cause 
of the increase in cone crops following release (142). 

Seed dissemination . --Seedfall usually begins during the early part of 
October and does not vary greatly with latitude (44). It reaches a peak very 
quickly and then declines. By January 1, 80 to 90 percent of the seed has 
fallen, although some continues to fall until late spring. Seedfall is hastened 
by dry, warm, windy weather and retarded by cool, wet weather (59) . Via- 
bility of the seed is highest at the peak of the seedfall. Seed falling later is 
progressively lower in viability until the end of seedfall in the spring. 

Although loblolly pine seed is entirely wind-disseminated, and was 
apparently carried 2.5 miles from the source in one case ( 104 ), it is usually 
not dispersed in effective quantities more than 300 feet. In strip cuttings in 
North Carolina, 67 percent of the seed fell within 100 feet and 85 percent 
fell within 200 feet of the windward uncut strip ( 101 ). In old fields, where 
seed dispersal was less restricted, the number of seedlings established fell 
below 1,000 per acre at 330 feet from the seed source, and beyond 462 feet 
was less than 500 per acre (83). 



10 



VEGETATIVE PROPAGATION 

When 1- to 3-year-old seedlings of loblolly pine are decapitated or in- 
jured, they sprout readily from buds formed in the axils of primary needles 
( _1_16, 1_17) . J/ Older seedlings and trees do not sprout. Rooting ability is 1/ 

similarly confined to young seedlings. Nearly half of the cuttings from 
1-year-old seedlings rooted, but only 6 percent rooted from 2-year-old 
seedlings, and none rooted from 3-year-old seedlings (49). Rooting by air- 
layering has been somewhat more successful. Six of ten 2|-year-old seed- 
lings developed roots in air- layers in one test ( 152 ), and good results were 
obtained with 3- and 5-year-old seedlings in another (20). In the latter test, 
results were poorer with older trees but air- layers even from 60-year-old 
trees developed a few roots. 

Loblolly pine has been successfully grafted by several methods. In 
very limited tests, one-half or more soft-tissue grafts were successful (_1_5_1). 
These included loblolly scions on loblolly and shortleaf stocks and shortleaf 
and slash scions on loblolly stocks. Side grafts of loblolly on loblolly were 
completely successful when made in April and somewhat less successful when 
made in February and March (31). Wedge grafts were least successful. 

SEEDLING DEVELOPMENT 

Establishment . - - Birds and rodents probably eat appreciable amounts of 
seed between seedfall and germination, but apparently not enough to hinder 
natural regeneration ( 143) except in poor seed years. Bob- white quail (Colinus 
virginianus ) in eastern Maryland have been found to eat pine seed in preference 
to wild and cultivated leguminous seed ( 145 ). However, as many as 89 percent 
of sound seeds may fail to germinate ( 100 , 126 ). Further losses occur because 
of limited moisture related to seedbed conditions and the failure of the radicle 
of germinating seeds to penetrate hard soil surfaces and deep litter ( 51 , 100 ). 

Moisture remains the most important factor in survival throughout the 
first growing season. The greatest mortality occurs shortly after germination 
( 47 ) and tends to be higher in lighter soils. Droughts after midsummer, when 
soil moisture is already quite low, may also cause heavy mortality, particularly 
where competing vegetation is abundant. A study in Arkansas showed that most 
new seedlings established on third-year and older seedbeds had disappeared by 
the following year (86), probably because of competition from hardwood brush. 

Losses from these various causes are reflected in the large number of 
sound seeds needed to establish a seedling, even on the best seedbed. In 
northeastern North Carolina, the number of sound seeds needed to establish 
1 seedling on fresh seedbeds averaged 9 on exposed mineral soil, 15 on burned 
soil surfaces, and 40 on undisturbed litter and logging slash ( 1 18 ). A similar 
effect of seedbed condition on seedling establishment was observed in south- 
eastern Arkansas (51). Thus, much larger amounts of seed are required for 



3/ Little, S. Official correspondence, Southeast. Forest Expt. Sta. 
1957. 



- 11 - 



satisfactory reproduction on undisturbed litter than on mineral soil. Favor- 
able seedbed conditions disappear rapidly, and about four times as many 
seeds are needed on second-year as on first-year seedbeds to establish one 
seedling 0J6, 120 , 141 ). By the third year, initially favorable seedbeds have 
become nearly as unfavorable as undisturbed litter. 

Natural regeneration of loblolly pine thus depends on adequate amounts 
of seed in the first year after logging or seedbed preparation ( 120 ). In small 
ownerships adequate seed can often be obtained by postponing harvest cutting 
until after seedfall. The seed-tree method gives the greatest control of the 
seed supply through variations in the numbers of seed trees ( 140 ), but adequate 
seed can also be obtained from seed strips. Seed is usually more plentiful in 
stands managed by the selection method because of the large number of seed- 
bearing trees and the stimulation of seed production by repeated cutting. 

Where the bulk of a well- stocked stand is cut, tractor logging exposes 
mineral soil on about 50 percent of the logged area, which is usually suffi- 
cient for satisfactory regeneration in good seed years ( 1 18 ). In mediocre 
seed years, however, or with less effective logging methods, additional site 
preparation is essential. Scarification with a bush-and-bog diskharrow or 
burning before or after logging have been successful ( 23 , 30 , 73 ) and will 
usually compensate for the lower seed supply in mediocre seed years. 
Periodic winter fires throughout the rotation, with the last fire just before 
the harvest, or several annual summer fires before the harvest, have also 
been tested with considerable success (7J3, 105 ). The effects of site prepa- 
ration on the amount of hardwood brush persist for several years, so that a 
greater percentage of established seedlings become dominant ( 75 , 143 ) . 

In poor seed years, the number of seed trees needed becomes prohib- 
itively large, even with intensive seedbed preparation, unless the seed trees 
are selected and released from competition 3 to 5 years before the harvest 
cut. In the South Atlantic Coastal Plain, released trees produce enough seed 
for adequate regeneration even in poor seed years ( 140 ). Since heavy cone 
crops are evident a year before maturity ( 1 19 ) and are usually followed by a 
poor crop 2 years later, poor seed years apparently can be predicted far 
enough in advance so that trees can be released in time to supply increased 
amounts of seed in the poor year ( 142 ). 

Early growth. --The resumption of growth in the spring is mainly a 
response to rising air temperature but is also influenced by soil temperature 
(64). -3/ It usually occurs before the date of the last killing frost (66), in late 
March or early April in the northerly portions and about a month earlier in 
the southerly portions of the range. Twenty percent or more of the year's 
height growth occurs each month from April to August and is usually at least 
80 percent complete by July 1 in all parts of the range (66^ 103, 144 ). Vigorous 
seedlings make several surges of height growth, normally three, during a 
growing season; the first is the longest and the last is usually very short (138). 



4/ Hahn, V. W. The effect of soil and air temperatures on the resump- 
tion of growth of tree seedlings in the spring. 1942. (Unpublished Master's 
thesis, Duke University, Department of Botany.) 

- 12 - 



Best growth occurs when night temperatures are 12 to 13 C. lower than day 
temperatures (JO). Thus, slowing of height growth in midsummer may be due 
in part to high night temperatures. High night temperatures may also be an 
important factor in the generally slower growth of loblolly pine along the Gulf 
Coast. Height growth ends in late summer, before air temperatures become 
unfavorable and apparently in response to shorter periods of daylight (64). 
Foliage is usually retained till the end of the second growing season,although 
it may be cast earlier if infected by the needle-blight fungi, chiefly Lophoder - 
mium pinastri and Hypoderma lethale (9^, 11). 

Roots of loblolly pine grow at all times of the year ( 103 , 123 ). Most 
root growth occurs in spring (April and May), and in late summer and early 
fall; least root growth occurs in winter and midsummer. Growth in winter 
is limited by low temperatures, none having been observed at less than 53° F. 
( 123 ). Growth in summer is limited by low soil moisture and high tempera- 
tures. Optimum temperature is 77° F. and root growth ceases between 86° 
and 95° (103). 

During the first 5 to 10 years, height growth of vigorous loblolly pine 
seedlings follows a rising trend, and may average 2.5 feet per year ( 12 , 127, 
138 ). Under favorable conditions, seedlings may reach 2 feet in height in the 
first year but the average first-year height is about 4 inches ( 102 ). In North 
Carolina, first-year seedling heights varied with soil surface conditions; the 
tallest 10 percent of seedlings present exceeded 11 inches in severely burned 
areas, 7 inches on bare soil or disturbed litter, and 5 inches in undisturbed 
litter, slash piles, and lightly burned spots. The better growth in severely 
burned areas was still evident at 5 years ( 138 ). Light shade apparently is 
beneficial in the first year (8); thereafter it is not. 

In the Coastal Plain of North Carolina, seedlings grew faster in sandy 
loams with friable subsoils than in silt loams with plastic subsoils ( 139 ). 
Seedlings on the better soils also had larger crowns. In a study of potted 
seedlings, growth was least in sand and best in a silty clay ( 136 ). Loosening 
of the soil by disking apparently aids height growth during the early years ( 139 ), 

Height growth of loblolly pine seedlings is inversely related to the stock- 
ing of larger trees within a 30- foot radius and directly related to level of 
shade ( 12_, J29 ) . In Arkansas, heights of 5-year-old seedlings ranged from 
0.8 foot under a full canopy to 10.0 feet in large openings ( 127 ). -^ In 8- to 
15-foot openings, seedlings were 2.6 feet tall in 5 years; this rate of growth 
was judged to be adequate for survival, but in smaller openings growth was 
less. In Georgia, the average seedling was 0.7 foot shorter for every 10-foot 
lower shade level (12). If the over-topping trees are hardwoods, seedling 
growth is still less- -in Arkansas seedlings were 0.14 foot shorter for every 
10 percent increase in the basal area of hardwood cover. -^ Seedlings growing 
beneath larger hardwood trees invariably die if they are not released. In a 



5/ Wahlenberg, W. G. Effect of overwood on survival and development 
of loblolly pine seedlings in southern Arkansas. 1946. (South. Forest Expt. 
Sta. office report.) 



13 



study in Louisiana, no seedling established under hardwood shade survived 
for more than 19 years, and the average period of survival was 5.27 years 
(29). Seedlings that grow less than 6 inches annually in height probably will 
not survive ^29, 127, 138 ). 

Low- level competition from hardwood shrubs and sprouts reduces 
height growth and is often fatal to loblolly pine seedlings. Approximately 80 
percent of overtopped 3-year-old and older seedlings and 15 to 40 percent of 
seedlings with side competition do not survive ( 109 , 138 ). Height growth and 
crown expansion of hardwood sprouts is rapid during the first 3 years and 
much slower thereafter (1_3_, 138) . Consequently, seedlings that are not over- 
topped at 3 years or later have a good chance of outgrowing the competing 
hardwoods. 

These variations in seedling growth are responses mainly to differences 
in light and soil moisture caused by competing hardwoods. The maximum rate 
of photosynthesis is greater in hardwoods than in loblolly pine, and the hard- 
woods reach their maximum rate at one- third or less of full sunlight (61, 68). 
Pine reaches its maximum rate at that light intensity only in the first year, 
because the primary needles are so arranged that they shade each other very 
little (8). But the arrangement of secondary needles on older seedlings results 
in much mutual shading ( 67 ) and photosynthesis proceeds in proportion to light 
intensity, reaching the maximum rate only in full sunlight (61, 68). Low light 
intensity also reduces photosynthesis through its effect on water absorption. 
Pine root systems are smaller than hardwood root systems under full light 
but the difference becomes much greater under partial light (34, 61, 62, 136 ). 
Thus, absorption is retarded under partial light, even when soil moisture is 
ample, and moisture stress in the seedlings is increased, which reduces the 
photosynthetic rate. When soil moisture is also low, the moisture stress in 
the seedlings is still greater. Thus, photosynthesis is reduced more rapidly 
in pine than in hardwoods by decreasing soil moisture C7, 59). 

Since low light intensity and low soil moisture usually occur together 
under natural conditions, loblolly pine suffers much more than the hardwoods 
from competition. In the first year, moisture is evidently the more important 
factor; in a study in North Carolina, pine seedlings in their first year did not 
respond to increased light at low moisture levels (47). After the first year, 
light is the more important factor; loblolly pine seedlings in the shade do not 
develop root systems large enough to supply the moisture needed for survival. 
With ample light, root systems are larger and supply the water and nutrients 
needed for survival even with soil moisture as low as that within a stand ( 69 , 
95). However, either deficient light or deficient soil moisture will retard 
growth; if both are deficient the seedlings usually die (60). 

Too much water may also be detrimental to seedling growth and sur- 
vival, although loblolly pine can endure prolonged flooding of the roots better 
than pond pine, its wet- land associate. One test of various periods of flood- 
ing showed that at least 10 months of continuous flooding with standing water 
was needed to permanently injure roots of loblolly pine seedlings (58). Pond 
pine showed permanent injury by failure to make normal height growth during 



- 14 - 



periodic drying after 3 months of continuous flooding. Another test showed 
that loblolly pine could endure flooding for a 50-percent longer period than 
pond pine.-"-/ 

Growth and survival of loblolly pine seedlings are also affected by in- 
sect and disease attacks. Repeated attacks by the Nantucket pine tip moth 
( Rhyacionia frustrana ) reduce height growth and cause crooking and forking 
but usually do not cause mortality. The pales weevil ( Hylobius pales ) and its 
close relatives may kill planted seedlings in large numbers in recently cut or 
burned areas but have not been important in natural reproduction. The red- 
headed pine sawfly ( Neodiprion lecontei ) and the pine webworm ( Tetralopha 
robustella) can cause mortality by defoliation and occasionally cause large 
losses in limited localities. In many localities west of the Mississippi the 
Texas leaf- cutting ant ( Atta texana ) is a serious pest on natural and planted 
seedlings, and control measures are necessary. 

The most common disease is fusiform rust ( Cronartium fusiforme). 
It causes lethal stem and branch cankers and has oak as an alternate host. 
The brown spot needle disease ( Scirrhia acicola ) is common in some areas 
and heavy infections probably check growth ( 10). 

SAPLING STAGE TO MATURITY 

Growth and yield . --Pure, even-aged stands of loblolly pine vary greatly 
in growth and yield in response to differences in site quality. Individual trees 
in particularly favorable locations may attain diameters of 50 to 60 inches and 
heights of 150 feet at advanced ages (2). The largest recorded loblolly pine 
presently in existence is located in Dinwiddie County, Virginia, and is 63 inches 
d.b.h. and 128 feet tall (1); another in Hertford County, North Carolina, is 54 
inches d.b.h. and 151 feet tall. The average tree is much smaller. Sizes 
attained by average trees in the dominant portion of well- stocked, unmanaged 
natural stands are shown in the tabulation below ( 125). Trees in managed stands 



would be 


considerably 


larger in 


d.b.h. at the same 


ages. 






Site Index 


60 feet 


Site Index 


90 feet 


Site Index 


120 feet 


Age 
(Years) 


D.b.h. 
(Inches) 


Height 
(Feet) 


D.b.h. 
(Inches) 


Height 
(Feet) 


D.b.h. 
(Inches) 


Height 
(Feet) 


20 


4.6 


32 


6.9 


48 


8.5 


64 


30 


6.6 


45 


9.6 


67 


11.9 


89 


40 


8. 1 


54 


11.7 


81 


14.6 


108 


50 


9.4 


60 


13.6 


90 


16.8 


120 


60 


10.4 


64 


15.0 


96 


18.6 


128 



6/ Gaiser, R. N. The growth of loblolly and pond pine seedlings under 
differing conditions of soil flooding. 1947. (Unpublished manuscript, Duke 
University, Department of Botany. ) 



15 



Because of its economic importance and wide range, several yield and 
growth studies of well- stocked natural stands of loblolly pine have been made 
(2, 79, 85, 125). One of these sampled the entire range of the species and 
indicated a maximum mean annual growth rate of 1,300 board-feet per acre 
(Int. 1/8-inch) in trees 6.6 inches d.b.h. and larger at 45 years, the age of 
culmination of mean annual increment for stands of 120-foot site index ( 125 ). 
On 60-foot sites the maximum rate was 318 board-feet per acre per year. 
Data from permanent sample plots in the Atlantic Coastal States indicated a 
possible current annual growth rate of 1,500 to 2,000 board-feet per acre 
(Int. 1/4- inch) in trees 9.6 inches d.b.h. and larger on the very best sites at 
age 55. Yields at 60 years in trees 6.6 inches d.b.h. and larger range from 
19,000 board-feet per acre (Int. l/8-inch) in well-stocked stands of 60-foot site 
index up to 73,000 board-feet per acre in stands of 120-foot site index ( 125 ). 

Mean annual cubic-foot growth in trees 1.6 inches d.b.h. and larger 
ranges from 76 cubic feet per acre at 35 years (culmination of MAI) on a 
60-foot site to 204 cubic feet per acre on a 120-foot site ( 125 ). Cubic-foot 
yields at 60 years in well-stocked stands vary from 2,400 cubic feet per acre 
on the poorest sites to nearly 12,000 cubic feet per acre on the best sites (79). 

Mean annual growth in standard cords in trees 3.6 inches d.b.h. and 
larger ranges from 0.88 cord per acre per year at 40 years in well-stocked 
stands of 60-foot site index up to 2.37 cords per acre per year at 35 years on 
120-foot sites ( 128 ). Yields of well-stocked stands at 60 years range from 
46 cords per acre on 60-foot sites to 121 cords per acre on 120-foot sites. 

In addition to varying with age and site quality, volume growth is 
strongly related to stand density, increasing with density up to a maximum 
that is higher on good sites than on poor sites (80). The volume growth of 
thinned stands also varies with age, site quality, and residual stocking. 
Recent studies by the Southeastern Forest Experiment Station suggest that 
the growth of thinned and unthinned stands does not differ greatly after one 
thinning when age, site quality, and stocking are equal. Although information 
presently available is insufficient to compare yields of managed and unman- 
aged stands, stands maintained at their optimum density by thinning through- 
out the rotation will undoubtedly produce more wood because most moribund 
trees will be salvaged and the residual trees will grow faster. 

Reaction to competition . --Loblolly pine is classed as an intolerant 
species, of the same degree of tolerance as shortleaf pine and Virginia pine, 
less tolerant than the oaks, and more tolerant than slash pine and longleaf 
pine (3). 

The more tolerant hardwoods readily become established in the under- 
story of loblolly pine stands, and on uplands throughout the range of loblolly 
pine the progress of plant succession is toward a hardwood, oak-hickory 
climax (94) . The succession can be most clearly seen in old-field stands 
(fig. 4). Light- seeded and intolerant hardwood species, such as sweetgum, 
red maple, yellow-poplar, blackgum, and waxmyrtle are early invaders. 
Somewhat later the components of the climax, oaks and hickories, appear. 



16 



... ,«e*4SWfe W 



W!$* 



■< 



i..' 



*»■>« 



OS**; 


^6 


•-. 1 






'■\^fc§ 



if Mt 



Thf r V"; 01d " f i eld StSnd ° f l0bl0ll y Pine in the Kisatchie National Forest Louisian* 
The understory of small hardwoods has developed since the stand was established 



- 17 



They increase in size and number as the pine stand matures (jj, 94) and re- 
place pines in the overstory as the stand disintegrates between 100 and 300 
years of age. Cutting of the pine stand without provision for reestablishment 
hastens the process, which accounts for the increase in hardwood types 
throughout the loblolly pine range. Fires during the dormant season have 
little effect on the succession because the hardwoods sprout prolifically and 
vigorously, and even annual dormant- season fires do not reduce the hard- 
wood crown area or number of stems (76). However, repeated fires at inter- 
vals of less than 10 years ultimately eliminate loblolly pine (30, 134) . Crown 
fires destroy the entire stand, as may hot surface fires during the growing 
season ( 17), but pine readily becomes reestablished if a seed supply is avail- 
able because the hardwoods are also killed back to the ground (93). 

Because it is intolerant of shade, loblolly pine expresses dominance 
early, and crowns differentiate rapidly under competition on good sites. In 
dense stands on poor sites, expression of dominance and crown differentia- 
tion are much slower. The density of undisturbed stands approaches an equi- 
librium at a rate that probably varies with site quality (21). Well-stocked 
stands ranged from 118.7 square feet of basal area per acre for trees 4 inches 
in d.b.h. up to 175.4 square feet for trees 16 inches d.b.h. ( 114 ). In 
Arkansas, well-stocked stands tended toward a basal area of 155 square feet 
per acre (28). 

Annual radial growth of loblolly pine is positively correlated with total 
rainfall from January to May and negatively correlated with temperature (33) . 
It reaches a maximum early in the growing season ( 149 ), and is directly pro- 
portional to crown ratio ( 54 , 71), crown length, and total height. -2/ Volume 
growth, however, also depends on the length of the clear stem. In 26- year- 
old trees, cubic volume growth of the clear stem was greatest with a crown 
length that was 40 percent of total tree height (71) . 

Loblolly pine prunes itself readily at younger ages, before branches 
develop heartwood. The maximum contribution to main- stem growth is made 
by branches in the upper portion of the crown, 15 percent of tree height from 
the top (71). Below this point the contribution becomes progressively less, 
until branches halfway down the stem contribute nothing. 

The increase in diameter growth after release is also directly related 
to crown ratio, but trees of large diameter respond less than trees of small 
diameter ( 26 , 78) . MacKinney (78) found that trees about 60 feet tall increased 
diameter growth more than shorter or taller trees after release. Thus, tall, 
slender trees with well-developed crowns, that is, codominants and better 
intermediates, respond best to release. Trees long suppressed also grow 
much faster in both height and diameter after release but may never attain 
the growth rate of trees that were never suppressed (26). Height growth 



7/ Dubow, D. A. The relationship between crown and bole length and 
their ratios with diameter growth in young loblolly pine plantations. 1953. 
(Unpublished Master's thesis, North Carolina State College, School of Forestry.) 



after release apparently depends mainly on age at release, while diameter 
growth depends on crown size and growing space. The capacity of loblolly 
pine to respond to release means that noncommercial removal of competing 
hardwoods is usually a profitable investment ( 15 , 112 ). 

Mortality in loblolly pine stands is caused mainly by competition (16, 
111 ), but fire, wind, lightning, sleet, disease, and insects may cause sub- 
stantial losses. Accidental fires may completely destroy stands, but more 
commonly reduce growth (_4) and cause stump wounds that permit the en- 
trance of decay fungi and insects and result in pitch soaking (50). Trees in 
repeatedly burned areas develop greater butt swell than unburned trees (2 7). 
Large, dominant trees are more vulnerable to wind damage than smaller 
trees ( 122 ), and trees with large cankers caused by the southern fusiform 
rust break more readily than sound trees ( 135 ). Although direct losses to 
lightning are small, averaging only 2 trees per 100 acres per year (122), 
lightning- struck trees often become centers of infestations by the southern 
pine beetle ( Dendroctonus frontalis) . Other injuries and drought conditions 
also favor this insect and it has killed large volumes of loblolly pine through- 
out the range. The engraver beetles ( Ips spp. ) and the black turpentine beetle 
( Dendroctonus terebrans ) may also cause serious losses under the same cir- 
cumstances (84). Sleet storms bend, break, and uproot many trees and may 
severely damage heavily stocked stands ( 82 , 91), particularly those made up 
of slender, small- crowned trees. Loblolly pine beyond the sapling stage is 
seldom killed by disease, but fungi cause appreciable cull in older stands. 
Heart rot ( Fomes pini ), entering through branch stubs, and butt rot ( Poly- 
porus schweinitzii) , entering through fire wounds, are the most important 
causes of such losses (56). 

After heavy partial cutting in older stands of moderate or higher den- 
sity, many residual trees die from causes directly related to logging and 
exposure. Intermediate and suppressed trees may succumb to the drastic 
change in environment ( 22 , 74). Isolated dominants and codominants, as in 
seed- tree stands, die at the rate of about 1 percent of the number of trees 
per year, mainly from wind and lightning ( 32 , 74 , 122 ). Logging injuries and 
bark-beetle attack are important causes of death in the first few years after 
cutting; puddling of heavy, wet soils and attendant root damage have also 
caused substantial losses (81). Ice damage to residual trees is negatively 
correlated with live- crown ratio, small- crowned spindling saplings being 
most vulnerable (92). 




19 - 



SPECIAL FEATURES 

In common with other hard pines, loblolly pine is highly resinous, al- 
though less so than slash pine and longleaf pine. The constitution of the 
oleoresin of loblolly pine is as follows (90): 

Density 0.8570 22 

Index of refraction 1.4675 2 ^-^ 

Specific rotation, degrees + 20.2 

Turpentine yield, percent 19 

Turpentine composition, percent 85 d-alpha-pinene 

12 1-beta-pinene 

The specific gravity of green loblolly pine wood averages 0.47 and 
increases from the pith outward. The trend is mainly due to age of the tree 
at the time the annual ring is formed and partly due to decreasing width of 
rings ( 147 ). Specific gravity is greatest near the base of the tree and de- 
creases with height; and it is greater in small- crowned than in large- crowned 
trees (97). It also increases as the percentage of summerwood increases. 

Tracheid length varies greatly from tree to tree, suggesting that it is 
strongly dependent on hereditary factors as well as on environmental con- 
ditions (6). Tracheid length averages 4.3 millimeters and ranges from 1.5 
up to 7.0 millimeters (14). It increases sharply from the pith outward during 
the first 10 years and at a slower rate beyond that point; it also increases 
from the base of the tree upwards to middle height and decreases above that 
level (6). 

The angle made by the fibrils (strands of cellulose that make up the 
tracheids) with the main axis of the tracheid is related to longitudinal stability 
of lumber and tearing strength of both sulfite and sulfate pulp made from the 
wood (98). Large fibril angles are associated with much shrinkage along the 
grain and lesser tearing strength of the pulp. Fibril angles in loblolly pine 
vary from 2 to 51 degrees, decrease from the pith outward and from the base 
of the tree upwards, and are smaller in narrower annual rings. Closely 
spaced trees with small crowns have smaller fibril angles than widely spaced, 
large- crowned trees. 



RACES AND HYBRIDS 

Distinct races of loblolly pine have not been identified and described, 
but definite variations in survival, growth rate, disease resistance, drought 
hardiness, and cold hardiness associated with seed source have been observed. 
In tests at several locations in the Southern and Central States, seedlings from 
north Alabama seed had a higher survival rate at 2 years than seedlings from 
Maryland and Virginia seed, while no seedlings from North Carolina and 
South Carolina survived (4_1). In other widely scattered tests in the South, 
seed from North Carolina and South Carolina has given better results (130). 



- 20 



Seedlings from seed of six different sources planted in southern Illinois 
showed a significantly different rate of height growth in the first year for 
each seed source (88). In another study, Maryland seedlings planted at a 
number of places throughout the south grew less in height than those from 
other locations, but had exceptionally well- developed fibrous roots ( 130 ). 

Near Bogalusa, Louisiana, trees from a local seed source were taller, 
larger in d.b.h. , and greater in cubic-foot volume per acre at 22 years than 
trees from Texas, Georgia, and Arkansas seed sources ( 129 ). In South Africa, 
loblolly pine trees from southern seed sources in the United States were taller 
at 9 years than those from northern sources, except that seedlings from 
Onslow County, North Carolina, were taller for their latitude, and seedlings 
from the Kisatchie National Forest in Louisiana and from the Crossett 
Experimental Forest in Arkansas were shorter ( 108 ). At Athens, Georgia, 
and Jasper, Texas, the variation in height growth with latitude of seed source 
was much less pronounced than in South Africa, but the good performance of 
the North Carolina strain and the poor behavior of the Louisiana and Arkansas 
strains showed up again ( 129) . 

Eastern strains of loblolly have shown a higher susceptibility to fusi- 
form rust infection than western strains. In the Bogalusa plantings, 37 per- 
cent of Georgia trees were infected, while infection of other strains ranged 
from 4 to 6 percent. In the Jasper and Athens plantings, eastern strains had 
a much higher incidence of rust than western strains, but northeastern strains, 
from Virginia and Maryland, had very few infections in either locality ( 129) . 

Cold resistance also varies with seed source. Seedlings of Virginia, 
Maryland, Tennessee, and Arkansas strains in nursery beds in southern 
Illinois were not damaged by subfreezing temperatures, but North Carolina 
seedlings sustained moderate damage, and South Carolina and Mississippi 
seedlings sustained moderate to severe damage (89). In Maryland, seed- 
lings from local seed were not injured by cold, but those from more southerly 
sources were damaged, the southern- most strain- -from Louisiana- -being 
conspicuously injured ( 130 ). 

Because of its well-known adaptability to a wide range of environmental 
conditions, loblolly pine has been planted in many places outside its range. It 
has been successfully grown in Australia, New Zealand, South Africa, and 
in the coastal region of Uruguay; in the United States it has been grown at 
Placerville, California, and in parts of Tennessee, southern Illinois, southern 
Indiana, western Kentucky, and southern New Jersey. In Pennsylvania and 
Massachusetts, seedlings are winter-killed; in Ohio and southern Indiana, 
needles commonly show cold injury (96). Cold also injures loblolly pine in 
the Ozarks ( 110 ) . 

In the "Lost Pines" area and at the western edge of its range in east 
Texas, where summer rainfall is often deficient, loblolly pine is apparently 
more drought hardy than it is farther east. In a test in east Texas, seed- 
lings from that locality had consistently better survival than seedlings from 
Louisiana, North Carolina, and Florida ( 154) . No differences in growth among 
the surviving seedlings were observed, however. 



- 21 



Variations in the behavior of individual trees have also been traced to 
hereditary factors. In South Carolina, seedlings from different mother trees 
differed significantly in height growth and survival (87). 

One natural hybrid involving loblolly pine has been identified and named. 
This is the hybrid known as Sonderegger pine (Pinus x sondereggeri) . It is 
common in Louisiana, and perhaps elsewhere, in longleaf stands near a source 
of loblolly pine pollen ( 25 , 43 ) . The seed apparently comes from longleaf pine 
trees; hence loblolly pine is probably the male parent. Many trees with char- 
acteristics intermediate between those of shortleaf and loblolly pine, which 
may be hybrids, have been found in east Texas ( 153) and may occur wherever 
these two species grow in mixture. Loblolly pine flowers before shortleaf pine 
but early conelets of shortleaf pine may become receptive while loblolly pine 
pollen is still being cast; or loblolly pine flowering may occasionally be re- 
tarded by cold weather so that loblolly pine conelets might still be receptive 
when shortleaf pine starts pollinating. Where loblolly and pond pine are 
closely associated, pines with intermediate characteristics between these 
two species are common. 

Interspecific hybrids of loblolly pine are not difficult to obtain (4_3) and 
a number of successful hybrids have been produced by controlled pollination. 
Some successful hybrids that have been reported are as follows (18, 19, 38, 
107, 133): 

Seed parent Pollen parent 

Shortleaf Loblolly 

Slash 

Pitch 

Longleaf " 

Loblolly Pitch 

Shortleaf x loblolly Loblolly 

Loblolly Shortleaf 

Slash 

Shortleaf x loblolly Loblolly x slash 

Loblolly x slash Slash 

Loblolly Sonderegger 

" Shortleaf x loblolly 

Shortleaf Shortleaf x loblolly 

Shortleaf x loblolly Loblolly x slash 

Shortleaf x slash Sonderegger 

Longleaf Sonderegger 

Seedlings from a cross between loblolly pine and South Florida slash 
pine ( Pinus elliottii var. densa) are growing at Hamilton, Georgia, and at 
the Southern Institute of Forest Genetics near Gulfport, Mississippi. -2/ 
Seedlings of pond x loblolly pine are growing at the Westvaco Experimental 
Forest, near Georgetown, South Carolina (37). 



&J Dorman, K. W. Official correspondence, Tidewater Forest 
Research Center, Franklin, Virginia. April 27, 1956. 

- 22 - 



LITERATURE CITED 

(1) American Forestry Association 

1956. THESE ARE THE CHAMPS. Part II. Amer. Forests 62(4): 33-40. 

(2) Ashe, W. W. 

1915. LOBLOLLY OR NORTH CAROLINA PINE. N. C. Geol. and Econ. Survey 

Bui. 24, 176 pp., illus. 

(3) Baker, F. S. 

1949. A REVISED TOLERANCE TABLE. Jour. Forestry 47: 179-181. 

(4) Barrett, L. I. 

1928. FIRE DAMAGE TO MATURE LOBLOLLY PINE. Naval Stores Rev. 38(18): 11. 

(5) and Downs, A. A. 

1943. HARDWOOD INVASION IN PINE FORESTS OF THE PIEDMONT PLATEAU. 

Jour. Agr. Res. 67: 111-127. 

(6) Bethel, J. S. 

1941. THE EFFECT OF POSITION WITHIN THE BOLE UPON FIBER LENGTH OF 

LOBLOLLY PINE. Jour. Forestry 39: 30-33. 

(7) Bormann, F. H. 
1953. FACTORS DETERMINING THE ROLE OF LOBLOLLY PINE AND SWEET- 
GUM IN EARLY OLD- FIELD SUCCESSION IN THE PIEDMONT OF NORTH 
CAROLINA. Ecol. Monog. 23: 339-358. 



1956. ECOLOGICAL IMPLICATION OF CHANGES IN THE PHOTOSYNTHETIC 

RESPONSE OF PINUS TAEDA SEEDLINGS DURING ONTOGENY. Ecology 
37: 70-75. 

(9) Boyce, J. S., Jr. 

1951. LOPHODERMIUM PINASTRI AND NEEDLE BROWNING OF SOUTHERN 
PINES. Jour. Forestry 49: 20-24. 

(10) 

1952. SCIRRHIA ACICOLA, A CAUSE OF LOBLOLLY PINE NEEDLE BROWNING. 
Assoc. South. Agr. Workers Proc. 49: 134. 

(11) 

1954. HYPODERMA NEEDLE BLIGHT OF SOUTHERN PINE. Jour. Forestry 52: 

496-498. 

(12) Brender, E. V., and Barber, J. C. 

1956. INFLUENCE OF LOBLOLLY PINE OVERWOOD ON ADVANCE 

REPRODUCTION. U. S. Forest Serv. Southeast. Forest Expt. Sta. 
Paper 62, 12 pp., illus. (Processed.) 

(13) and Nelson, T. C. 

1954. BEHAVIOR AND CONTROL OF UNDERSTORY HARDWOODS AFTER CLEAR 

CUTTING A PIEDMONT PINE STAND. U. S. Forest Serv. Southeast. Forest 
Expt. Sta. Paper 44, 17 pp., illus. (Processed.) 

(14) Brown, H. P., and Panshin, A.J. 

1940. COMMERCIAL TIMBERS OF THE UNITED STATES. 554 pp., illus. 

New York and London. 



23 



(15) Bull, H. 

1945. INCREASING THE GROWTH OF LOBLOLLY PINE BY GIRDLING LARGE 

HARDWOODS. Jour. Forestry 43: 449, 450. 

(16) 



1950. CORD MORTALITY IN UNTHINNED STANDS. U. S. Forest Serv. South. 

Forest Expt. Sta. South. Forestry Notes 70. (Processed.) 

(17) Byram, G. M. 

1948. VEGETATION TEMPERATURE AND FIRE DAMAGE IN SOUTHERN PINES. 

U. S. Forest Serv. Fire Control Notes 9(4): 34-36. 

(18) California Forest and Range Experiment Station 

1948. TIMBER PINE HYBRIDIZATION. Ann. Rpt. 1947: 13, 14. 

(19) 



1952. NEW HYBRIDS RESULT FROM EARLIER ATTEMPTS. Ann. Rpt. 1952: 13, 14. 

(20) Cech, F. 

1955. VEGETATIVE PROPAGATION OF LOBLOLLY PINE. Texas Forest Serv. 

Cir. 51, 13 pp., illus. 

(21) Chaiken, L. E. 

1939. THE APPROACH OF LOBLOLLY AND VIRGINIA PINE STANDS TOWARD 

NORMAL STOCKING. Jour. Forestry 37: 866-871. 

(22) 



1941. GROWTH AND MORTALITY DURING 10 YEARS FOLLOWING PARTIAL 

CUTTINGS IN LOBLOLLY PINE. Jour. Forestry 39: 324-329. 

(23) and LeGrande, W. P., Jr. 

1949. WHEN TO BURN FOR SEEDBED PREPARATION. Forest Farmer 8(11): 4. 

(24) Chandler, R. F., Schoen, P. W., and Anderson, D. A. 

1943. RELATION BETWEEN SOIL TYPES AND THE GROWTH OF LOBLOLLY 

PINE AND SHORTLEAF PINE IN EAST TEXAS. Jour. Forestry 41: 505, 506. 

(25) Chapman, H. H. 

1922. A NEW HYBRID PINE ( PINUS PALUSTRIS X PINUS TAEDA ). Jour. Forestry 

20: 729-735. 

(26) 



1923. THE RECOVERY AND GROWTH OF LOBLOLLY PINE AFTER SUPPRESSION. 

Jour. Forestry 21: 709-711. 



(27) 



(28) 



(29) 



(30) 



1942. EFFECT OF ANNUAL SPRING FIRES ON STUMP TAPER OF LOBLOLLY 

PINE. Jour. Forestry 40: 962, 963. 



1942. MANAGEMENT OF LOBLOLLY PINE IN THE PINE-HARDWOOD REGION 

IN ARKANSAS AND IN LOUISIANA WEST OF THE MISSISSIPPI RIVER. Yale 
Univ., School Forestry Bui. 49, 150 pp., illus. 



1945. THE EFFECT OF OVERHEAD SHADE ON THE SURVIVAL OF LOBLOLLY 

PINE SEEDLINGS. Ecology 26: 274-282. 



1948. HOW TO GROW LOBLOLLY PINE INSTEAD OF INFERIOR HARDWOODS. 

Soc. Amer. Foresters Proc. 1947: 347-353. 



24 



(31) Chase, S. B. , and Galle, F. C. 

1954. PINE GRAFTING. Tenn. Valley Authority Tech. Note 18. 

(32) Clark, S. F., and Hebb, E. A. 

1951. MORTALITY FOLLOWING HARVEST CUTTING. U. S. Forest Serv. South. 

Forest Expt. Sta. South. Forestry Notes 74. (Processed.) 

(33) Coile, T. S. 

1936. THE EFFECT OF RAINFALL AND TEMPERATURE ON THE ANNUAL 

RADIAL GROWTH OF PINE IN THE SOUTHERN UNITED STATES. Ecol. 
Monog. 6: 533-562. 

(34) 



1940. SOIL CHANGES ASSOCIATED WITH LOBLOLLY PINE SUCCESSION ON 

ABANDONED AGRICULTURAL LAND OF THE PIEDMONT PLATEAU. 
Duke Univ. Forestry Bui. 5, 85 pp., illus. 



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1948. RELATION OF SOIL CHARACTERISTICS TO SITE INDEX OF LOBLOLLY 

AND SHORTLEAF PINES IN THE LOWER PIEDMONT OF NORTH CAROLINA. 
Duke Univ. Forestry Bui. 13, 78 pp., illus. 

(36) and Schumacher, F. X. 

1953. RELATION OF SOIL PROPERTIES TO SITE INDEX OF LOBLOLLY AND 

SHORTLEAF PINES IN THE PIEDMONT REGION OF THE CAROLINAS, 
GEORGIA, AND ALABAMA. Jour. Forestry 51: 739-744. 

(37) Committee on Southern Forest Tree Improvement 

1956. WESTVACO COLLECTS OVER 5,000 POUNDS OF SEED. Newsletter 5(1): 5. 

(38) 



1956. EXTENSIVE HYBRIDIZATION IS CARRIED OUT AT THE SOUTHERN 

STATION. Newsletter 5(1): 7. 

(39) Cooper, W. E. 

1942. FOREST SITE DETERMINATION BY SOIL AND EROSION CLASSIFICATION. 

Jour. Forestry 40: 709-712. 

(40) Craighead, F. C. 

1950. INSECT ENEMIES OF EASTERN FORESTS. U. S. Dept. Agr. Misc. Pub. 

657, 679 pp., illus. 

(41) Cummings, W. H. 

1952. LOBLOLLY PINE SHOWS EARLY DIFFERENCES WITH SOURCE OF SEED 

AND LOCALITY OF PLANTING. Jour. Forestry 50: 626, 627. 

(42) Doak, K. D. 

1934. FUNGI THAT PRODUCE ECTOTROPHIC MYCORRHIZAE OF CONIFERS. 

Phytopathology 24: 7. 

(43) Dorman, K. W. 

1950. THE GENETICS OF SOUTHERN PINES. U. S. Forest Serv. Southeast. 

Forest Expt. Sta., 52 pp., illus. (Processed.) 

(44) and Barber, J. C. 

1956. TIME OF FLOWERING AND SEED RIPENING IN SOUTHERN PINES. U. S. 

Forest Serv. Southeast. Forest Expt. Sta. Paper 72, 15 pp., illus. (Processed.) 

(45) Downs, A. A. 

1947. CHOOSING PINE SEED TREES. Jour. Forestry 45: 593, 594. 

(46) Easley, L. T. 

1954. LOBLOLLY PINE SEED PRODUCTION AREAS. Jour. Forestry 52: 672, 673. 

- 25 - 



(47) Ferrell, W. K. 

1953. EFFECT OF ENVIRONMENTAL CONDITIONS ON SURVIVAL AND GROWTH 

OF FOREST TREE SEEDLINGS UNDER FIELD CONDITIONS IN THE PIED- 
MONT REGION OF NORTH CAROLINA. Ecology 34: 667-688. 

(48) Gaiser, R. N. 

1950. RELATION BETWEEN SOIL CHARACTERISTICS AND SITE INDEX OF 

LOBLOLLY PINE IN THE COASTAL PLAIN REGION OF VIRGINIA AND 
THE CAROLINAS. Jour. Forestry 48: 271-275. 

(49) Gardner, F. E. 

1929. THE RELATIONSHIP BETWEEN TREE AGE AND THE ROOTING OF 

CUTTINGS. Amer. Soc. Hort. Sci. Proc. 26: 101-104. 

(50) Garren, K. H. 

1941. FIRE WOUNDS ON LOBLOLLY PINE AND THEIR RELATION TO DECAY AND 

OTHER CULL. Jour. Forestry 39: 16-22. 

(51) Grano, C. X. 

1949. IS LITTER A BARRIER TO THE INITIAL ESTABLISHMENT OF SHORTLEAF 

AND LOBLOLLY PINE REPRODUCTION? Jour. Forestry 47: 544-548. 

(52) 



1951. WHAT LOBLOLLIES ARE LIKELY CONE PRODUCERS'' Jour. Forestry 

49: 734. 



(53) 



1957. INDICES TO POTENTIAL CONE PRODUCTION OF LOBLOLLY PINE. Jour. 

Forestry 55: 890, 891. 



(54) Guttenberg, S. 

1953. LOBLOLLY CROWN LENGTH- -CLUE TO VIGOR. U. S. Forest Serv. South. 

Forest Expt. Sta. South. Forestry Notes 88. (Processed.) 

(55) Hatch, A. B. 

1937. THE PHYSICAL BASIS OF MYCOTROPHY IN PINUS. Black Rock Forest 
Bui. 6, 168 pp., illus. 

(56) Hepting, G. H. , and Chapman, A. D. 

1938. LOSSES FROM HEART ROT IN TWO SHORTLEAF AND LOBLOLLY PINE 
STANDS. Jour. Forestry 36: 1193-1201. 

(57) Hocker, H. W., Jr. 

1956. CERTAIN ASPECTS OF CLIMATE AS RELATED TO THE DISTRIBUTION 

OF LOBLOLLY PINE. Ecology 37: 824-834. 



(58y 



Hunt, F. M. 

1951. EFFECTS OF FLOODED SOIL ON GROWTH OF PINE SEEDLINGS. Plant 

Physiol. 26: 363-368. 

(59) Jemison, G. M. , and Korstian, C. F. 

1944. LOBLOLLY PINE SEED PRODUCTION AND DISPERSAL. Jour. Forestry 

42: 734-741. 

(60) Korstian, C. F., and Bilan, M. V. 

1957. SOME FURTHER EVIDENCE OF COMPETITION BETWEEN LOBLOLLY 

PINE AND ASSOCIATED HARDWOODS. Jour. Forestry 55: 821, 822. 

(61) Kozlowski, T. T. 

1949. LIGHT AND WATER IN RELATION TO GROWTH AND COMPETITION OF 

PIEDMONT FOREST TREE SPECIES. Ecol. Monog. 19:207-231. 



26 



(62) Kozlowski, T. T., and Scholtes, W. H. 

1948. GROWTH OF ROOTS AND ROOT HAIRS OF PINE AND HARDWOOD SEED- 

LINGS IN THE PIEDMONT. Jour. Forestry 46: 750-754. 

(63) Knight, F. B. 

1951. SURVEY GIVES NEW INFORMATION ON INSECT DAMAGE TO LOBLOLLY 

PINE CONES. Forest Farmer 10(11): 8. 

(64) Kramer, P. J. 

1936. EFFECT OF VARIATION IN LENGTH OF DAY ON GROWTH AND DORMANCY 

OF TREES. Plant Physiol. 11: 127-137. 

(65) 



1942. SPECIES DIFFERENCES WITH RESPECT TO WATER ABSORPTION AT LOW 

SOIL TEMPERATURES. Amer. Jour. Bot. 29: 828-832. 



(66) 



1943. AMOUNT AND DURATION OF GROWTH OF VARIOUS SPECIES OF TREE 

SEEDLINGS. Plant Physiol. 18: 239-251. 



(67) and Clark, W. S. 

1947. A COMPARISON OF PHOTOSYNTHESIS IN INDIVIDUAL PINE NEEDLES AND 

ENTIRE SEEDLINGS AT VARIOUS LIGHT INTENSITIES. Plant Physiol. 22: 
151-157. 

(68) and Decker, J. P. 

1944. RELATION BETWEEN LIGHT INTENSITY AND RATE OF PHOTOSYNTHESIS 

OF LOBLOLLY PINE AND CERTAIN HARDWOODS. Plant Physiol. 19: 350-358. 

(69) Oosting, H. J., and Korstian, C. F. 

1952. SURVIVAL OF PINE AND HARDWOOD SEEDLINGS IN FOREST AND OPEN. 
Ecology 33: 427-430. 

(70) Kramer, P. J. 

1957. SOME EFFECTS OF VARIOUS COMBINATIONS OF DAY AND NIGHT TEM- 

PERATURES AND PHOTOPERIOD ON HEIGHT GROWTH OF LOBLOLLY 
PINE SEEDLINGS. Forest Sci. 3: 45-55. 

(71) Labyak, L. F., and Shumacher, F. X. 

1954. THE CONTRIBUTION OF ITS BRANCHES TO THE MAIN-STEM GROWTH OF 

LOBLOLLY PINE. Jour. Forestry 52: 333-337. 

(72) Little, E. L., Jr. 

1953. CHECK LIST OF NATIVE AND NATURALIZED TREES OF THE UNITED 
STATES (INCLUDING ALASKA). U. S. Dept. Agr. Handbook 41, 472 pp. 

(73) Little, S., and Mohr, J. J. 

1954. REPRODUCING PINE STANDS ON THE EASTERN SHORE OF MARYLAND. 

U. S. Forest Serv. Northeast. Forest Expt. Sta. Paper 67, 11 pp. (Processed.) 

(74) 



1957. GROWTH AND MORTALITY OF RESIDUAL LOBLOLLY PINES AFTER A 

SEED- TREE CUTTING. U. S. Forest Serv. Northeast. Forest Expt. Sta. 
Forest Res. Note 75, 4 pp. (Processed.) 



(75) 



1957. SEEDBED TREATMENT INCREASES DOMINANCE OF NATURAL LOBLOLLY 

PINE REPRODUCTION. U. S. Forest Serv. Northeast. Forest Expt. Sta. 
Forest Res. Note 76, 4 pp. (Processed.) 

(76) Lotti, T. 

1956. ELIMINATING UNDERSTORY HARDWOODS WITH SUMMER PRESCRIBED 

FIRES IN COASTAL PLAIN LOBLOLLY PINE STANDS. Jour. Forestry 54: 
191, 192. 

- 27 - 



(77) Lotti. T. 

1956. GOOD SEED PRODUCTION FROM A YOUNG STAND OF LOBLOLLY PINE. 

U. S. Forest Serv. Southeast. Forest Expt. Sta. Research Note 97, 2 pp., 
illus. (Processed.) 

(78) MacKinney, A. L. 

1933. INCREASE IN GROWTH OF LOBLOLLY PINES LEFT AFTER PARTIAL 

CUTTING. Jour. Agr. Res. 47: 807-821. 

(79) and Chaiken, L. E. 

1939. VOLUME, YIELD, AND GROWTH OF LOBLOLLY PINE IN THE MID- 
ATLANTIC COASTAL REGION. U. S. Forest Serv. Appalachian Forest 
Expt. Sta. Tech. Note 33, 30 pp., illus. (Processed.) 

(80) McClay, T. A. 

1955. THE RELATION OF GROWTH TO SITE AND RESIDUAL DENSITY IN LOB- 
LOLLY PINE PULPWOOD STANDS. U. S. Forest Serv. Southeast. Forest 
Expt. Sta. Res. Note 78, illus. (Processed.) 

(81) McCulley, R. D. 

1950. WET WEATHER LOGGING MAY DAMAGE SEED TREES. Va. Forests 5(5): 6. 

(82) McKellar, A. D. 

1942. ICE DAMAGE TO SLASH PINE, LONGLEAF PINE, AND LOBLOLLY PINE 

PLANTATIONS IN THE PIEDMONT SECTION OF GEORGIA. Jour. Forestry 
40: 794-797. 

(83) McQuilkin, W. E. 

1940. THE NATURAL ESTABLISHMENT OF PINE IN ABANDONED FIELDS IN 
THE PIEDMONT PLATEAU REGION. Ecology 21: 135-147. 

(84) Merkel, E. P., and Kowal, R. J. 

1956. FOREST INSECT CONDITIONS IN THE SOUTHEAST. U. S. Forest Serv. 
Southeast. Forest Expt. Sta. Paper 67, 9 pp., illus. (Processed.) 

(85) Meyer, W. H. 

1942. YIELD OF EVEN- AGED STANDS OF LOBLOLLY PINE IN NORTHERN 

LOUISIANA. Yale Univ., School Forestry Bui. 51, 39 pp., illus. 

(86) 



1955. SOME TREATMENT EFFECTS ON LOBLOLLY AND SHORTLEAF PINE 

REPRODUCTION. Jour. Forestry 53: 895-900. 

(87) Minckler, L. S. 

1942. ONE-PARENT HEREDITY TESTS WITH LOBLOLLY PINE. Jour. Forestry 

40: 505, 506. 

(88) 



1950. EFFECT OF SEED SOURCE ON HEIGHT GROWTH OF PINE SEEDLINGS. 

Jour. Forestry 48: 430, 431. 



(89) 



1951. SOUTHERN PINE FROM DIFFERENT GEOGRAPHIC SOURCES SHOW 

DIFFERENT RESPONSES TO LOW TEMPERATURES. Jour. Forestry 
49: 915, 916. 

(90) Mirov, N. T. 

1954. CHEMICAL COMPOSITION OF GUM TURPENTINES OF THE U. S. AND 

CANADA. Jour. Forest Prod. Res. Soc. 4: 1-7. 

(91) Muntz, H. H. 

1947. ICE DAMAGE TO PINE PLANTATIONS. South. Lumberman 175(2201): 

142-145. 

- 28 - 



(92) Nelson, T. C. 

1951. ICE DAMAGE HIGH FOR SPINDLY RESIDUAL SAPLINGS. Forest Farmer 

10(11): 6. 

(93) Oosting, H. J. 

1944. THE COMPARATIVE EFFECT OF SURFACE AND CROWN FIRE ON THE 

COMPOSITION OF A LOBLOLLY PINE COMMUNITY. Ecology 25: 61-69. 

(94) 



1948. PLANT COMMUNITIES. 389 pp. , illus. San Francisco. 

(95) and Kramer, P. J. 

1946. WATER AND LIGHT IN RELATION TO PINE REPRODUCTION. Ecology 

27: 47-53. 

(96) Parker, J. 

1950. PLANTING LOBLOLLY PINE OUTSIDE ITS NATURAL RANGE. Jour. 

Forestry 48: 278, 279. 

(97) Pillow, M. Y. 

1954. SPECIFIC GRAVITY RELATIVE TO CHARACTERISTICS OF ANNUAL 

RINGS IN LOBLOLLY PINE. U. S. Forest Serv. Forest Prod. Lab. Rpt. 
1989, 8pp., illus. (Processed.) 

(98) Terrell, B. Z., and Hiller, C. H. 

1953. PATTERNS OF VARIATION IN FIBRIL ANGLES IN LOBLOLLY PINE. U. S. 

Forest Serv. Forest Prod. Lab. Rpt. D1935, 31pp., illus. (Processed.) 

(99) Pomeroy, K. B. 

1949. LOBLOLLY PINE SEED TREES: SELECTION, FRUITFULNESS, AND 
MORTALITY. U. S. Forest Serv. Southeast. Forest Expt. Sta. Paper 5, 
17pp., illus. (Processed.) 

(100) 



1949. THE GERMINATION AND INITIAL ESTABLISHMENT OF LOBLOLLY PINE 

UNDER VARIOUS SURFACE SOIL CONDITIONS. Jour. Forestry 47: 541-543. 

(101) and Korstian, C. F. 

1949. FURTHER RESULTS ON LOBLOLLY PINE SEED PRODUCTION AND 

DISPERSAL. Jour. Forestry 47: 968-970. 

(102) and Trousdell, K. B. 

1948. THE IMPORTANCE OF SEED-BED PREPARATION IN LOBLOLLY PINE 

MANAGEMENT. South. Lumberman 177(2225): 143, 144. 

(103) Reed, J. F. 

1939. ROOT AND SHOOT GROWTH OF SHORTLEAF AND LOBLOLLY PINES IN 

RELATION TO CERTAIN ENVIRONMENTAL CONDITIONS. Duke Univ. 
Forestry Bui. 4, 52 pp., illus. 

(104) Reynolds, R. R. 

1933. NATURAL REPRODUCTION OF SHORTLEAF AND LOBLOLLY PINE OVER 

LONG DISTANCES. U. S. Forest Serv. Bui. 17(17): 3. 

(105) Riebold, R. J. 

1955. PRESCRIBED BURNING IN LOBLOLLY PINE MANAGEMENT. Fourth Ann. 

Forestry Symposium Proc. 1955: 92-99. 

(106) Righter, F. I. 

1939. EARLY FLOWER PRODUCTION AMONG THE PINES. Jour. Forestry 37: 

935-938. 

(107) and Duffield, J. W. 

1951. INTERSPECIES HYBRIDS IN PINES. Jour. Heredity 42: 75-80. 

- 29 - 



(108) Sherry, S. P. 

1947. THE POTENTIALITIES OF GENETIC RESEARCH IN SOUTH AFRICAN 

FORESTRY. British Empire Forestry Conference, 11pp., illus. 

(109) Shipman, R. D. 

1954. RELEASE OF LOBLOLLY PINE BY VARIOUS WEEDING METHODS. U. S. 

Forest Serv. Southeast. Forest Expt. Sta. Res. Note 65. (Processed.) 

(110) Shoulders, E. 

1952. COLD HURTS LOBLOLLY IN OZARKS. U. S. Forest Serv. South. Forest 

Expt. Sta. South. Forestry Notes 82. (Processed.) 

(111) Simmons, E. M., and Schnur, G. L. 

1937. EFFECT OF STAND DENSITY ON MORTALITY AND GROWTH OF LOB- 

LOLLY PINE. Jour. Agr. Res. 54: 47-58. 

(112) Smith, L. F. 

1947. EARLY RESULTS OF A LIBERATION CUTTING IN A PINE-HARDWOOD 

STAND IN NORTHERN LOUISIANA. Jour. Forestry 45: 278-282. 

(113) Society of American Foresters 

1954. FOREST COVER TYPES OF NORTH AMERICA (EXCLUDING MEXICO). 

Soc. Amer. Foresters. 67 pp., illus. 

(114) Stahelin, R. 

1949. THINNING EVEN-AGED LOBLOLLY AND SLASH PINE STANDS TO 
SPECIFIED DENSITIES. Jour. Forestry 47: 538-540. 

(115) Steirly, C. C. 

1952. THE RED- COCKADED WOODPECKER. Va. Wildlife 13(8): 18, 19. 

(116) Stone, E. L. ( Jr., and Stone, M. H. 

1943. DORMANT BUDS IN CERTAIN SPECIES OF PINUS. Amer. Jour. Bot. 

30: 346-351. 

(117) and Stone, M. H. 

1954. ROOT COLLAR SPROUTS IN PINE. Jour. Forestry 52: 487-491. 

(118) Trousdell, K. B. 

1950. SEED AND SEEDBED REQUIREMENTS TO REGENERATE LOBLOLLY 
PINE. U. S. Forest Serv. Southeast. Forest Expt. Sta. Paper 8, 13 pp., 
illus. (Processed.) 

(119) 



1950. A METHOD OF FORECASTING ANNUAL VARIATION IN SEED CROP FOR 

LOBLOLLY PINE. Jour. Forestry 48: 345-348. 



(120) 



(121) 



(122) 



1954. FAVORABLE SEEDBED CONDITIONS FOR LOBLOLLY PINE DISAPPEAR 

3 YEARS AFTER LOGGING. Jour. Forestry 52: 174-176. 



1954. PEAK POPULATION OF SEED-EATING RODENTS AND SHREWS OCCURS 

1 YEAR AFTER LOBLOLLY STANDS ARE CUT. U. S. Forest Serv. South- 
east. Forest Expt. Sta. Res. Note 68, illus. (Processed.) 



1955. LOBLOLLY PINE SEED TREE MORTALITY. U. S. Forest Serv. Southeast. 

Forest Expt. Sta. Paper 61, 11 pp., illus. (Processed.) 

(123) Turner, L. M. 

1936. ROOT GROWTH OF SEEDLINGS OF PINUS ECHINATA AND PINUS TAEDA. 

Jour. Agr. Res. 53: 145-149. 

- 30 - 



(124) U. S. Department of Agriculture 

1941. CLIMATE AND MAN. Agr. Yearbook 1941, 1,248 pp., illus. 

(125) U. S. Forest Service 

1929. VOLUME, YIELD, AND STAND TABLES FOR SECOND- GROWTH SOUTHERN 

PINES. U. S. Dept. Agr. Misc. Pub. 50, 202 pp., illus. 

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1948. WOODY-PLANT SEED MANUAL. U.S. Dept. Agr. Misc. Pub. 654. 416 pp., 

illus. 

(127) Wahlenberg, W. G. 

1948. EFFECT OF FOREST SHADE AND OPENINGS ON LOBLOLLY PINE SEED- 

LINGS. Jour. Forestry 46: 832-834. 

(128) Wakeley, P. C. 

1947. LOBLOLLY PINE SEED PRODUCTION. Jour. Forestry 45: 676, 677. 

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1951. IMPORTANCE OF GEOGRAPHIC STRAINS. In Report of the First Southern 

Conference on Forest Tree Improvement. 9 pp. 



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1953. PROGRESS IN STUDY OF PINE RACES. South. Lumberman 187(2345): 137- 140. 

(131) 

1954. PLANTING THE SOUTHERN PINES. U. S. Dept. Agr. Monog. 18, 233 pp., 
illus. 

(132) Weddell, D. J. 

1935. VIABLE SEED FROM NINE-YEAR-OLD SOUTHERN PINE. Jour. Forestry 

33: 902. 

(133) Weidman, R. H. 

1947. TREES IN THE EDDY ARBORETUM. U. S. Forest Serv. Calif. Forest 

and Range Expt. Sta. Forest Res. Note 53, 8 pp. (Processed.) 

(134) Wells, B. W. 
1928. PLANT COMMUNITIES OF THE COASTAL PLAIN OF NORTH CAROLINA 

AND THEIR SUCCESSIONAL RELATIONSHIPS. Ecology 9: 230-242. 

(135) Wenger, K. F. 

1950. THE MECHANICAL EFFECT OF FUSIFORM RUST CANKERS ON STEMS 

OF LOBLOLLY PINE. Jour. Forestry 48: 331-333. 

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1952. EFFECT OF MOISTURE SUPPLY AND SOIL TEXTURE ON THE GROWTH 

OF SWEETGUM AND PINE SEEDLINGS. Jour. Forestry 50: 862-864. 



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1954. THE STIMULATION OF LOBLOLLY PINE SEED TREES BY PRE-HARVEST 

RELEASE. Jour. Forestry 52: 115-118. 



1955. GROWTH AND PROSPECTIVE DEVELOPMENT OF HARDWOODS AND 

LOBLOLLY PINE SEEDLINGS ON CLEARCUT AREAS. U. S. Forest 
Serv. Southeast. Forest Expt. Sta. Paper 55, 19 pp., illus. (Processed.) 



1955. HEIGHT GROWTH OF LOBLOLLY PINE SEEDLINGS IN RELATION TO 

SEEDLING CHARACTERISTICS. Forest Sci. 1:158-163. 



- 31 



(140) Wenger, K. F. 

1955. SEED TREE REQUIREMENTS IN LOBLOLLY PINE. South. Lumberman 

191(2393): 116-118. 

(141) 



1956. COMMENTS ON "SOME TREATMENT EFFECTS ON LOBLOLLY AND 

SHORTLEAF PINE REPRODUCTION." Jour. Forestry 54: 194, 195. 



(142) 



1957. ANNUAL VARIATIONS IN THE SEED CROPS OF LOBLOLLY PINE. Jour. 

Forestry 55: 567-569. 



(143) and Trousdell, K. B. 

1957. THE NATURAL REGENERATION OF LOBLOLLY PINE IN THE SOUTH 

ATLANTIC COASTAL PLAIN. U. S. Dept. Agr. Forest Serv. Production 
Res. Report 13, 78 pp., illus. 1957. 

(144) Williston, H. L. 

1951. HEIGHT GROWTH OF PINE SEEDLINGS. Jour. Forestry 49: 205. 

(145) Wilson. K. A., and Vaughn, E. A. 

1944. THE BOB-WHITE QUAIL IN EASTERN MARYLAND. Md. Game and Inland 

Fish Comn. 138 pp. 

(146) Wright, J. W. 

1952. POLLEN DISPERSION OF SOME FOREST TREES. U. S. Forest Serv. 
Northeast. Forest Expt. Sta. Paper 46, 42 pp., illus. (Processed.) 

(147) Yandle, D. O. 

1956. STATISTICAL EVALUATION OF THE EFFECT OF AGE ON SPECIFIC 

GRAVITY IN LOBLOLLY PINE. U. S. Forest Serv. Forest Prod. Lab. 
Rpt. 2049. 4pp., illus. (Processed.) 

(148) Young, H. E. 

1947. CARBOHYDRATE ABSORPTION BY THE ROOTS OF PINUS TAEDA . 

Queensland Jour. Agr. Sci. 4(1/6): 1-6. 

(149) and Kramer, P. J. 

1952. THE EFFECT OF PRUNING ON THE HEIGHT AND DIAMETER GROWTH 

OF LOBLOLLY PINE. Jour. Forestry 50: 474-479. 

(150) Zahner, R. 

1954. ESTIMATING LOBLOLLY PINE SITES IN THE GULF COASTAL PLAIN. 
Jour. Forestry 52: 448, 449. 

(151) Zak, B. 

1955. THE GRAFTING OF SHORTLEAF AND OTHER PINE SPECIES. U. S. 
Forest Serv. Southeast. Forest Expt. Sta. Paper 59, 13 pp., illus. (Processed.) 

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1956. EXPERIMENTAL AIR- LAYERING OF SHORTLEAF AND LOBLOLLY PINE. 

U. S. Forest Serv. Southeast. Forest Expt. Sta. Paper 69, 12 pp., illus. 
(Processed. ) 

(153) Zobel, B. J. 

1953. ARE THERE NATURAL LOBLOLLY-SHORTLEAF PINE HYBRIDS? Jour. 

Forestry 51: 494, 495. 

(154) and Goddard, R. E. 

1955. PRELIMINARY RESULTS ON TESTS OF DROUGHT HARDY STRAINS OF 

LOBLOLLY PINE ( PINUS TAEDA L. ). Texas Forest Serv. Res. Note 14, 
23pp., illus. (Processed.) 

_ 32 - Agriculture - Asheville